Hydraulic brake system



Jan. 2, 1940. L. s. BITTNER HYDRAULIC BRAKE SYSTEM Filed July 12, 1938 I lllllll III III awe/whom 1 fear 5. Bur/v5? Patented Jan. 2, 1940 2,185,535

1 UNITED STATES PATIENT OFFlCE HYDRAULIC BRAKE SYSTEM Leroy S. Bittner, Elysburg, Pa. Application July 12, 1938, Serial N0. 218,866

2.Claims. (Cl. 3384) This invention relates to a hydraulic brake and carrying the friction bands or shoes l 6 riv system for Wheeled vehicles and more particueted to the outer face thereto. The upper ends larly to an improved hydraulic brake having of the webs are spaced apart though pivotally means for automatically compensating for the connected to links lBf', which in turn are pivoted 5 Wear on the brake shoes in association with apto hydraulic piston rods 20 attached to pistons 5 paratus which will prevent loss of fluid from 25 carried in pressure cylinder 22, which is fastthe braking system, if a fluid supply pipe is rupened to the dust plate 52. The pistons 2B are tured or leaking. moved outwardly by the introduction between While automatic shoe compensators have been them through fluid port 25 of fluid pressure to' lo heretofore suggested, the structures proposed force the friction bands or shoes to into contact l have not functioned properly and in the most with the brake drum iii. A coil spring 26 is instances involved constructions, which were exafiixed to the upper ends of the web members pensive to manufacture and delicate in opera- H to insure that the bands it will be out of tion. The automatic wear compensator contemengagement with the drum except when fluid l plated by the present invention is simple, rugged pressure, is exerted on the pistons. w

and absolutely reliable. However, it is most desirable to normally posi- A further object of the improved hydraulic tion the friction bands I6 just out of contact braking system is the'safety cut-oil device used with the drums so that comparatively small fluid in combination with the wear compensator pressure and consequentoutward movement of which will close 01f a section of the hydraulic the shoes is necessary to adequately apply the 20 fluid conduits, if a conduit becomes ruptured brakes, and also to compensate for wear of the or leaks to a degree sufficient to ineffectively apbands as their surfaces are worn down from ply the brakes. use. These two important factors are solved by In the drawing, the use of a combined wear compensator and Fig.- 1 is a diagrammatical showing of the hyband adjuster which comprises an arcuate 25 draulic braking system as applied to a motor toothed segment 30 riveted or welded to the cenvehicle; tral portion l2 of the dust plate, a segment 30 Fig. 2 is a vertical medial section of a hybeing supplied for each brake shoe. As shown draulic brake assembly embodying the present in detail in Fig. 3, each segment cooperates with 3 invention; a double dog or pawl 3|, whose spaced parallel 30 Fig/Bis an enlarged fragmental view of one offset arms 32 and 33 are rigidly secured at of the automatic brake band compensating deslightly different angles on the squared ends of vices; r shaft 34 provided with an enlarged circular mid Fig. 4 is a fragmentary horizontal sectional DO O which is mounted in Opening 35 35 view of the compensating device taken on line bored through the angle arm of the web mem- 35 44 of Fig. 3; ber H. A coil tension spring 31 is hooked in Fig. 5 is a vertical longitudinal section of the the r 32 and the Web 11 to exerta downward hydraulic pressure creating mechanism for 5311- pull on the pawls to urge them into engageergizing the brakes. v ment with the teeth 38 cut on the inner arcuate' 40 As illustrated in Fig. 1 the present invention face of segment, i 40 pertains to a hydraulic brake mechanism for 'use The weal COmDeIISatmg mechanlsm p S6 IS on motor Vehicles and comprises in its broad ed in y cope d e applica Se u aspects a plurality of internally expanding wheel 1161 254,555, fi March 1939- brakes B joined by suitable pressure piping P It is highly desirable to incorporate 1n a hyto a hydraulic preSsure creating mechanism C. 'draulic braking system using a wear compen- Each wheel brake B consists of a brake drum sator as above described, a fl pressure ncarried on or formed integrally with .d t erator and conduit system which will automatplate ll having a central section I2 to which cally lose ff aseption of the ndui r pinthe circular plate I3 is bolted. Secured to the ing sy m if th section becomes ruptured or is plate I3 is a downwardly extending fulcrum rod leaking ba y With resulting 1088 Of fl and I that terminates in a horizontal pivot I5 to. fluid P u whlch the expending brake shoes I6 are hinged. Following the Pascal theory that fluid pres- Each shoe comprises a substantially semi-circusure travels undiminished in all directions, it lar T cross-section metal web member I! havwill be evident that, if a rupture or leak occurs ing a lower end l8 for embracing the pivot H: in the conduit system, the fluid pressure will decrease and none of the brakes can be effectively applied. Therefore, the present invention includes means for sealing ofi the section or piping which is losing pressure.

Referring to Fig. 5, it will be observed that the fluid pressure generator C comprises a foot,

lever 40 positioned on the floor of the automobile for operation by the driver. The pedal 40 is connected by linkage 4| to the horizontally reciprocating piston 42 mounted in cylinder 43 to discharge the fluid into the conduit system P through outlet 44.

While each brake may have an individual piping system, the invention is shown with two main branches leading from the pressure generator C to the front and rear sets of brakes as units. Mounted above the outlet 44 of cylinder 43 is an elongated chamber 45 to the ends of which the unit branch pipes P are connected. The chamber 45 is enlarged on either side of the discharge opening 44'as indicated by numerals 46,

the enlargements being spherical while the continuation of the chamber beyond the spherical portions 46 is tubular. A valve device comprising a hollow or half ball 41, having an-outwardly extending horizontal stem 48 passing through perforated plate 49, is placed in each of the spherical enlargements 46 so that under certain conditions the valve and stem may move or float outwardly to seal the outer tubular portions of the chamber 45. To insure that under ordinary operating conditions the ball valves 41 will be maintained in theirgopen position, notches 50 are formed in the valve stem for engagement with a spring pressed ball 5|, which is urged downwardly by coil spring 52 secured in casing 53.

In Fig. 5 the valves 41 are in open position so that when the foot pedal 40 is applied the piston 42 will compress the hydraulic fluid in the systhe valves 41 on its stem 48 outwardly to seal" the ruptured pipe unit. The second notch 50 nearest to the valve will then be engaged by the.

ball 5| to positively hold the valve in sealed position.

After the piping system has been repaired and it is desired to reopen the ball valve, it is a comparatively simple matter to remove one of the plates 54 and press the valve stem 48 backwardly until. the ball 5| snaps into the other notch 50.

A fluid reserve reservoir 55 is integrally formed with or mounted directly above compression cylinder 43 with an opening 55 therebetween, so that the system per se is maintained full of fluid at all times. Fillerv cap 51 is provided for adding additional fluid into the reservoir 55. To warn the driver of the vehicle when a leak has occurred in the system and pressure has dropped or when the reservoir needs replenishing with additional fluid, a suitable gauge 58 is placed on the vehicle dash board and communicates with the reservoir 55. l I

It will be appreciated by those skilled in the art that the automatic brake shoe compensat ing means, as above described, insures that the outward expanding movement of the brake shoes is substantially the same under all .conditions. That is, by taking up the wear as it occurs in small amounts the movement of the pistons and brake shoes remain substantially the same and, therefore, the foot operated compression piston in the fluid reservoir also moves substantially the same under all conditions.

If, however, a leak or rupture occurs in any portion of the conduit system, the fluid in the system either under its own internal pressure or by influence of the compression piston will rush bythe ball valves and move them outwardly to seal off the conduit, which is losing compression, and eflectively seal the same so that the conduits uneffected will operate as before.

What I claim is:

1. In a hydraulic brake apparatus, a cylinder, a piston adapted to move therein, a fluid reservoir secured to and in communication with said cylinder and adapted to maintain said apparatus full of fluid, an outlet passage for said cylinder, a dual valve housing secured thereto, said housing comprising similar outwardly extending chambers, a common inlet to said housing arranged intermediate' the said chambers, each of said chambers having an enlarged globular portion intermediate its length, a vertical perforated plate mounted in the elongated section, a valve having a stem extending through the perforated plate, said valve being normally positioned adjacent the center of the said globular portion, and a fluid conduit extending to a brake actuator from the outer end of said chamber, the said valve-being adapted to seat against spherical wall of the said globular portion when the valve is subjected to an abnormal flow of fluid passing through said chamber.

2. In a hydraulic brake apparatus, a fluid pressure cylinder having a piston movable therein, an integral reserve fluid reservoir formed above and in communication with said cylinder, a fluid outlet for said cylinder, a dual valve chamber secured-intermediate its ends and communicating with said fluid outlet, fluid conduits leading from the ends of said chamber to brake actuating mechanisms, the said valve chamber having spaced apart enlarged globular portions formed therein, individual se'mi cylindrical valves mounted in each globular portion, the stems of said valves extending into the outer portions of said dual chamber and through perforated plates mounted in said outer portions for supporting the ends of the valve stems and spring pr sed balls cooperating with grooves in said stems for holding said individual valves in openor closed position.

LEROY S. BITTNER. 

